Alcove Tolerance Calculator
Clearances, scribes and installation strategy for alcove units
Alcove tolerance calculator
Coming soon: height & skirting
Height clearance and skirting/architrave options will be added in a future update.
We build the carcass 100mm narrower than your reference width and supply two 50mm L-shaped fillers that screw to the cabinet sides. This makes installation easier and avoids wall fixings.
Understanding your result
TCS Filler Fit: We build the carcass 100mm narrower than your reference width and supply two 50mm L-shaped fillers that screw to the cabinet sides. Beginners use MIN (tightest); experienced/trade can use MAX for a wider unit.
Build width is the carcass width you should cut. For scribe/shadow/loose fit, we base off the tightest point.
Side clearance is the gap each side for positioning. Scribe allowance is extra material to trim to the wall.
Install method reflects risk from variation and skill. High variation + beginner = consider split carcass or professional help.
Alcove tolerances explained
Why walls are rarely straight
Plaster, older construction and settling cause alcoves to taper, bow or slope. The tightest point controls your build.
Scribes vs filler panels vs shadow gaps
Scribe — trim a panel to the wall for a clean fitted look. Best for traditional.
TCS Filler Fit — our default: carcass 100mm narrower, two 50mm L-shaped fillers fixed to cabinet sides. Generic filler panels — calculated thickness each side.
Shadow gap — intentional visible gap (6–12mm). Modern look; no scribing.
How to measure an alcove
Measure width at top, middle and bottom (front face). Use the smallest. If they differ by >10mm, you have taper or bow.
Common UK problems
Skirting and architrave reduce usable depth. Bowed walls are tightest in the middle. Sloping floors affect height clearance.
Frequently asked questions
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How much clearance do I need for an alcove unit?
Typically 4–8mm per side for trade, 6–10mm for experienced DIY, 10–16mm for beginners. The calculator adjusts for your skill and fit style.
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What is a scribe panel?
A scribe is an extra panel or the edge of the carcass that you trim with a scribing tool to match the wall profile. It hides gaps on uneven walls.
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Should I leave a gap either side?
Yes — a small service clearance (4–8mm per side) allows you to position the unit and avoids binding. For a clean fit, add scribe allowance on top.
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My alcove is wider at the top — what do I do?
Build to the tightest width (usually the bottom). The variation tells you how much scribe or filler you need. Enter both min and max width for best results.
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Do I need filler panels?
TCS Filler Fit is our default: we build the carcass 100mm narrower and supply two 50mm L-shaped fillers that screw to the cabinet sides. Generic filler panels are an alternative — the calculator can recommend thickness based on your alcove variation.
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How do I handle skirting boards?
Either cut back the skirting where the unit sits, or notch the plinth. Enter your usable depth at skirting level if you have it. The tool can flag depth issues.
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Can I install a full-height unit as one piece?
If variation is low and you have ceiling clearance, yes. For high variation or sloping ceilings, the calculator may recommend a split carcass (base + upper) for easier install.
